<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			div
{
	border:2px solid #a1a1a1;
	padding:10px 40px; 
	background:#dddddd;
	width:300px;
	border-radius:20px;
}
		</style>
	</head>
	<body>
		<div>border-radius 属性允许您为元素添加圆角边框！ </div>
	</body>
</html>
